1. Technical Field
The present invention relates to correction methods of a transport amount, and medium transport apparatuses.
2. Related Art
Medium transport apparatuses for transporting a medium, such as inkjet printers, are already well known. Some of these medium transport apparatuses are provided with a transport roller for transporting a medium by rotating, and a movement amount detecting section for detecting a movement amount of the medium.
Even when the transport roller transports a medium by a target transport amount, the actual movement amount of the medium may not agree with the target transport amount, and a so-called transport error may occur. It is known that the actual movement amount of a medium when the transport roller transports the medium by a predetermined transport amount (target transport amount) changes in accordance with a rotational position of the rotating transport roller. Thus, the transport error also changes in accordance with the rotational position.
In the cases where such a transport error occurs, the transport amount when the transport roller transports the medium needs to be corrected. More specifically, the transport amount needs to be increased or decreased from the target transport amount such that the actual movement amount of the medium agrees with the target transport amount.
A conventional medium transport apparatus is provided with a rotational position detection sensor for detecting the rotational position of the transport roller, and a storing section that stores transporting property information of the transport roller, which indicates a change in the actual movement amount according to the rotational position. The transport error is obtained using the transporting property information, based on the rotational position that has been detected by the rotational position detection sensor, and the transport amount is corrected based on the obtained transport error.
However, providing the rotational position detection sensor is too costly, and thus there has been a demand for a medium transport apparatus that can correct the transport amount as appropriate without providing the rotational position detection sensor.
It should be noted that JP-A-05-96796 is an example of related techniques.